The rate of each complication was three to four times greater than seen in women who did not have psoriasis, Dr. Xinaida Lima of Harvard University and Massachusetts General Hospital in Boston and colleagues reported in their poster presentation here at the American Academy of Dermatology meeting.

The presenters offered cautiously worded conclusions to their study.

"This exploratory study highlights some possible associations between psoriasis and pregnancy events," Lima and colleagues said in conclusion.

"Future studies should address this important research question with prospective design or more comprehensive retrospective cohort," they added.

Authorities agree that pregnancy adversely affects psoriasis in most cases, but mixed results have come from studies evaluating associations in the opposite direction. Indeed, the study also suggested that women with psoriasis had a significantly lower rate of cesarean section compared with women who did not have the inflammatory skin disease.

Meanwhile, some past evidence has indicated psoriasis increases the risk of certain pregnancy complications, such as recurrent spontaneous abortion and hypertension. Other research has turned up no association between psoriasis and poor pregnancy outcomes.

Lima and colleagues sought to clarify the associations between psoriasis and pregnancy in a review of medical records for women with psoriasis diagnoses in the Partners healthcare system who became pregnant between 1999 and 2009.

For comparison, the investigators compiled a matched control group of women who did not have psoriasis.

The review identified 358 psoriasis patients who had had at least two diagnoses for psoriasis and 131,424 women who were similar except for no psoriasis diagnosis.

Preliminary statistical analysis showed that the women with psoriasis had significantly higher rates of five pregnancy complications:

Spontaneous abortion, 28.1 percent versus 7.2 percent

Preterm birth, 21.7 percent versus 7.4 percent

Severe preeclampsia and eclampsia, 14.2 percent versus 2.9 percent

Placenta previa with and without hemorrhage

Ectopic pregnancy, 13.6 percent versus 3 percent

The C-section rate in the psoriatic patients was about a third that of the group without psoriasis, and that remained significant even after differences in race and obesity were taken into account.